The hydroformylation reaction, also known as the oxo reaction, is used extensively in commercial processes for the preparation of aldehydes by the reaction of one mole of an olefin with one mole each of dihydrogen (H2) and carbon monoxide. One use of the reaction is in the preparation of normal and isobutyraldehyde from propylene. The normal and isobutyraldehyde obtained can be converted into many commercially valuable chemical products such as, for example, n-butanol, 2-ethylhexanol, n-butyric acid, isobutanol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, and esters thereof.
Control of the production of a particular isomer of butyraldehyde is thus useful matching the supply of n- and iso-butyraldehydes to the demand of products derived from them. For some commercial users, n-butyraldehyde selectivity is highly desired for the production of n-butanol and a wide variety of catalysts have been developed to favor the normal isomer, i.e. high n/i ratio. A significant amount of research has also been dedicated to the development of hydroformylation catalysts to produce more of the branched isobutyraldehyde, characterized by having an iso content higher than 50%. It remains desirable to develop catalysts for the propylene hydroformylation process achieving a high isoselectivity, especially in higher temperature reaction conditions such as 75-130° C.